Sprocket.



UNTTED sTATEs PATENT oEEIoE.

4emmer: s. LEWIS, or OAK PARK,

ILLINOIS, AssreNoa To MEAD CYCLE COMPANY, or

CHICAGO, ILLINOIS, ,A CORPORATION OF ILLINOIS.

srnocxET.

Bpeeication of Letters Patent;

` Patented Jan. 1, 1918.

Application filed October 27, 191,6. Sleri'al No. 128,050.

To all whom t may concern: l

Be it known that I, GEORGE S. LEWIS, a citizen of the United States, residing at yOak Park, in the county of Cook and State, Y of Illinois,have invented a Vnew' and useful.

Improvement in Sprockets', of which the following is a specification.

My invention relates morefparticularly to improvement in the art'of manufacturing sprockets forming the front drivingsprockets of bicycle constructions.

My primary objects are to `providefa sprocket presentingthe desired strength and Wearing qualities and which may be manu factured at less cost than spnpckets 'as hitherto manufactured, and which shall be lighter in Weight."V

R ferring to the'accompanying drawings,

Figures 1 to 15, inclusive, illustrate certain,

of the stepswhioli may be performed in pro ducing my improved sprocket, Figs. 1, 2 and 5 being face views of the blank from which `the sprocket is formed and showing. it in different-,stages-of construction, and Figs.

.3. and 4, sections taken-'at the lines Sand 4, respectively, on Figsl and 2 and viewed in the direction of the arrows. Fig. 6 vis a `face view showingby dotted lines the blank in the 'stage nimmediately 'preceding its finished sta e,- and by full lines the connpleted sproc et; and. Fig. 7, a section takenv at the line7 'on Fig. 6 and viewed in the direction ofthe arrow.

It may be stated at the outset thatit is oneV of the 4purposes of the invention, as Vreferajblypractised,` to form the sprocketr atpiece of sheet steel, thel grade of steel being. at4 usually employed 41n the manu- `facture of sprockets as hitherto constructed. In roducing' my Vim roved sprocket I pref era ly-'usfe'apiece o 'sheet'steel and refery ably .lirstblank it to circular shape, y any suitable means, as shown in Figs. 1 and 3,

'and of a diameter s1ighny-greaer-then that., 4 5

ofthe finishedsprocket.The .blank thus formed' isV then 4introduced-into Va press of l any desirableconstruction. for dravving'tlle peripheral ortion Vofthe blank to form'the 1 oiset" annu ar 'portion 8, and the center -of the blank is -also drawnto form .the central offset portion 9 preferably of theirregular contourshown `in Fig. 2, .these o erations,

if desired, being simultaneous.` he blank thus Oset is.. then introducedinto another` press of any suitable constructlon "and parte` of the metal are stamped therefrom to produce the openings'shown in Fig. 5. The

blank is then inserted into another press to rough out .the teeth of `the gear,-as represented bythe dotted lines in FigtS; and the Ateeth then I Iilled or otherwlse operated on to cause them' to be of the proper size, as indicated ag 10.

In' thge :finished sprocket 'it will be noted that the metal. of the sprocket is practically of uniform .thickness and that the teeth 10,

by reason of being formedV in the oft'set-` .cycle Whichwould extend 'adjacent the outer surface of the sprocket when the'A parts are assembled in a cranlchanger. i

`The provision` ofthe oHset portion `8 of the sprocket is of great importance vin that the fact that this part is in a different plane from'that in which thepart of the sprocket adjacent to this offset part is located, forms an annular;4 rib-portion which adds great stren th tothe structure' and permits the sproc etto 'be formed of relatively thin- 'metal, andl this `increased strength is aug mented by the fact that in operating on the susV blank, as described, to producejthisoifset portion 8, the metal at the point Where the offsetting takespla'ce' is.' drawn and is thereby hardened; l -4 Another advantage is presented-by'form-` ing the sprocket-Wheel as stated, in tl`1at the,A

4formation of the offset portion Sfdoes lnot producelthe hardening vofthe 4extreme circmferential portionfo'f'the blank'and from which the sprocket-teeth are 'to be formed, .i

and thus the cutting of'A theteeth yis formed on'relatively soft metal, and this is true whether the teeth 'befirst' roughed out and then afterward milled, as Iexplained above, or ,otherwiseV finished, 'orjwhether Y they are produced by milling, or thelike operation, enly, '.Ofcourse it will be under# stood that if it--is desired to harden the` wagj p y, f ertain successive operations in prducing the sprocketsvvheel. have-been describedA teeth', this" may be' done Ain any desirable above, but'it will be readily understood that,

4if desired, the order of the steps may be altered and certain operations consolidated.

It will be understood from the foregoing that asproeket-wheel constructed in accordance with m invention is not `only of light Weight, sti ,and presents -the desired de ee of durability, but may be very readily anreconomically manufactured.

What I claim as new by Letters Patent is- 1. A sheet metal sprocket of substantially uniform thickness throughout yits extent havinga central hub portion, an outerl peripheral portion provided with radially extending teeth lfling substantially in the me-- dial plane of t e sprocket, and an intermediate body portion, said body portion and hub portion lying and desire to secure' in planes oiset with revangle to said axls.l .spect to the medial plane.

2. A sprocketl of substantially uniform thickness havin peripheral portlon with teeth extending radially therefrom 'atfsubstantially .rightangles'to the axis of the sprocket, and an intermediate body portion, said body portion and hub portion lyin radially extending teeth". i

3. Al sprocket .of substantially 4uniform thickness throughout itsjextent and having its outer edge portion offset relatively to the plane o the adjacent portion of the body of the. sprocket 'andV its central portion o iiset, said outer. edge portion extending in y at'ariht angle tor a' plane substantial the axis Aof the sprocket, an containing teeth, extending substantially` at a righ GEORGE s. LEWIS.

in planes at o -v posite sides respectively o the plane of sald a central hubport'ion, a 

